The subject matter disclosed herein relates to the art of power plants and, more particularly, to method of meeting a purge flow requirement for a power plant.
Prior to light off or ignition, a gas turbomachine (GT) undergoes a purge cycle to expel combustible gases from non-combustion portions of the system. Conventional systems define the purge cycle in terms of purge time at a predetermined purge speed. During a purge cycle, air is introduced into the GT. Once firing speed is achieved, a timer is initiated. The GT continues to accelerate to purge speed and the purge cycle then continues until a predetermined time has passed. Once the predetermined time has passes, the GT typically decelerates to firing speed. Generally, a lower airflow passed through the system while accelerating from firing speed to purge speed is compensated for by the additional airflow after the timer has stopped and the GT decelerates from purge speed to firing speed.